From my first encounter with Airbnb I have been a fan. I’ve used the service and then extolled its virtues. I’ve been a kind of evangelist, convinced that my most hotel-obsessed friends would catch Airbnb fever if they just gave it a chance.

I’ve used Airbnb close to a dozen times in total. Until recently, it was difficult for me to perceive any potential weaknesses for guests within the service. (Hosts are a bit more vulnerable than guests, as highlighted by that particularly well-covered and quite terrible incident last year. To its credit, Airbnb introduced a $50,000 vandalism and theft guarantee in response to that event.)

I recently discovered a weakness of Airbnb for guests, which I’ll try to summarize as the uneasy pairing of a host’s limitations and a guest’s expectations.

Here’s my example. A few weeks ago I rented an Airbnb apartment in an exciting corner of a big city. There were two issues with the rental: a miscommunication around the key, which led me to the conclusion that the host only possessed a single set of keys to the flat, and a strong hint that the rental was not approved. My evidence for this latter assumption was that the house rules instructed guests not to answer the front door and to tell neighbors, if asked, that they were friends of the owner.

Here’s the thing, the key misunderstanding and its terrible inconvenience for my host aside. Given the choice I would never have opted to stay in a clandestine rental, and nor would I have wanted to be the sole key holder of an apartment owned by somebody I had never met. Unwanted complications almost seem to be guaranteed in such situations.

For me, the beauty of Airbnb has been the friendly, effortless simplicity of the experience, with the happy bonuses of local knowledge and invitations to coffee. But with the stress of feeling that the single set of keys in your possession is your host’s lifeline to his living space, or the worry that your very presence in your host’s building is clandestine, the experience begins to feel neither effortless nor simple.

And this is the crux of the issue. With Airbnb it’s hard to know in advance whether your needs as a guest will match up with the particularities of a host’s situation.